Devices have been used to apply adhesive to work pieces such as automotive bodywork for a number of years. Such devices have ranged from simple nozzles which dispense a bead of material in a line according to the motion of the robot to swirl type applicators such as those shown on U.S. Pat. Nos. 3,911,173; 4,031,854; and 4,098,632. Efforts have also been made to provide a swirl pattern in U.S. Pat. Nos. 4,659,018 and 5,322,564.
While such devices are effective in some applications, often they lack the versatility necessary to perform a wide variety of operations using the same applicator.
It is therefore an object of this invention to provide a single application device which is capable of dispensing material having a wide range of viscosities in both wirling and streaming patterns and which provides accurate control over the bead characteristics of the material applied.
It is further an object of this invention to provide a dispenser which is capable of being used with all manual and automatic sealant and adhesive dispense valves and associated equipment and which can be used for applications such as PVC, hem flange, liquid mask, body shop and trim shop applications.
This dispensing apparatus consists of eight main components. The first component is a bellows, dust cap or other cover which is used to protect the end of the device and prevent adhesive materials and other potentially damaging particles from entering the device. Secondly, bearings are provided to allow the parts to rotate relative to one another. In the preferred embodiment ball or spherical bearings are used, however it is understood that other types of bearings such as polymeric bearings may be utilized to allow relative rotation of parts.
A motor is used to provide rotational energy and in the preferred embodiment the rotational speeds may be up to 32,000 RPM. Optionally, on the back of the motor is a rotary encoder which is used to determine the angular position of the motor shaft. The motor shaft is in turn attached to a rotating shaft which has on the end thereof a off-center aperture such the diameter of the orbit imparted is approximately {fraction (1/16)}xe2x80x3 in the preferred embodiment. Of course larger or smaller orbits may be used as desired and such modifications are easily within the ambit of one skilled in the art.
Extending through the center of the rotating shaft and separated by an annular space therefrom is a through shaft which in the preferred embodiment is formed of a solid stainless steel tube that flexes and which is capable of retaining pressures of upwards of 3500 psi (including a substantial safety factor). This stainless steel tube allows the through shaft to flex and transport the material to be dispensed to the tip which may be anything from a simple single aperture to shaped or multiple apertures located at the end of the through shaft. Alternatively, a hose having a braided steel covering may be used for a through shaft.
Thus, one apparatus (and tip) can be used to provide multiple separate, unique and desirable application patterns (stream and swirl) and further allows reduced maintenance compared to existing systems. It is believed that the instant invention also allows faster material application and robotic applications and allows exact control over the dispensing pattern. It is also further allows independent control of the flow and bead pattern, such independent control being more difficult in the known prior art.
The bead pattern of the material can be accurately controlled by varying the following factors: standoff distance of apparatus from substrate, material pressure, motor speed, rotating shaft hole offset, nozzle tip and feed rate (rate at which the applicator moves with respect to the substrate). By changing these factors, the bead width can be varied from less than one inch to several inches. The bead height can also be varied over any range desirable and additionally the bead pattern can be open or closed (whether the substrate is entirely covered or not covered along the length where material has been deposited).
It is further understood that located inside the through shaft may be a static mixer which is in turn connected to an inlet for multiple component materials. Such an apparatus allows application of multicomponent materials while at the same time having the extreme flexibility with respect to applications set forth above for the basic single component material apparatus.
These and other objects and advantages of the invention will appear more fully from the following description made in conjunction with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views.